HP 54750A, User Manual, Page: 172 / 478

The Digital Communications
Analysis Menus
Measure Eye Menu
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Crossing %
Crossing percentage is a measure of the location of the eye crossing points
relative to the separation between V
top
and V
base
. Typically , it is desirable to
have the crossing points located midway between V
top
and V
base
. In this case
the crossing percentage would be 50% according to the following formula:
C r ossing per cent = 100
V
c r o s s
0 V
b a s e
V
t o p
0 V
b a s e
V
top
and V
base
are calculated from a histogram using data within the eye
window as dened in the Dene Measure menu.
V
cross
is the most prevalent vertical location or amplitude of the crossing
points . A horizontal histogram over the entire display is used to determine
the time location of the crossing points . Narrow vertical histograms are then
used to determine the vertical location of V
cross
.
K ey Path 4 Shift 5 4 Meas ey e 5
N
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
Crossing %
6-36